Swainsonine free base is an indolizidine alkaloid having biological activity, including the inhibition of many mannosidases. Syntheses of the free-base alkaloid have been described, such as (a) Pearson and Hembre, J. Org. Chem., 1996, 61:7217-7221; (b) Carpenter, N. M. et al., Tet. Lett. 1989, 30:7261-7264; (c) Bennett, R. B., III et al., J. Am. Chem. Soc., 1989, 111:2580-2582; (d) Takahata, M. et al., The Alkaloids, vol. 44 Academic Press, New York (1993), at 189; (e) Miller, S. A., et al., J. Am. Chem. Soc. 1990, 112:8100-8112; and (f) Cohen, N., et al., J. Am. Chem. Soc. 1983, 105:3661-3672. Additional syntheses are described in U.S. Pat. No. 5,187,279 (Cha) and U.S. Pat. No. 5,075,448 (Fleet). Pearson and Hembre claim to produce 4.5 g of swainsonine free base in 20% yield from the lactone intermediate (2,3-O-isopropylidene-D-erythronolactone) using a method which requires eleven steps, three chromatographic separations and four crystallizations (at 7218, column 2). According to Pearson and Hembre, as of their 1996 publication, attempts to scale up even the shortest known synthetic route had been unsuccessful (at 7217, column 1).